The ancient Chinese preparation, chhü, is usually made from wheat or rice, and includes several different kinds of mold as well as the yeasts that will eventually produce the alcohol. Some of the wheat may be roasted or left raw, but most is steamed, coarsely ground, shaped into cakes, and then left to mold in incubation rooms for several weeks. Species of Aspergillus grow on the outside, and species of Rhizopus and Mucor on the inside. Aspergillus is the same kind of mold used to digest soybeans to make soy sauce and Rhizopus is the major mold in soybean tempeh, while Mucor is important in some kinds of aged cheeses. All of them accumulate starch- and protein-digesting enzymes, and generate trace byproducts that contribute flavor. Once the grain cakes have been well permeated with microbes, they’re dried for storage. When needed for mi chiu production, they’re soaked in water for several days to reactivate the microbes and their enzymes.